The present invention relates to three-way type valves for controlling the flow of liquids. More particularly, it relates to a tri-port cylinder valve used to control the flow of semi-liquid compositions and liquid-borne solids. The valve structure according to the invention is particularly suited for controlling process and waste liquid stream in the meat and poultry packing industry where scrap meat, bone fragments, hide, feathers and other waste materials are often pumped via pipelines throughout a processing plant. It is not uncommon, for example, to find as much as 85% by weight solid materials having diameters of up to 3 and 4 inches as the principal flow component in such process streams. Because semi-liquid compositions are considerably higher in viscosity than comparable liquids having no solid particulates, they generally require high pressures and temperatures in order to be effectively transported by way of conventional piping.
Various control problems presented by such severe process conditions have been alleviated by the present invention. Under high pressure and temperature conditions, it is essential that the flow of liquid to processing equipment such as a transfer pump remain free of restriction due to solid materials becoming clogging within the valves or piping structure. It is also important that a process control valve downstream of such equipment be capable of quickly and effectively reversing or altering the flow of a semi-liquid stream high in solids volume without danger of a flow restriction in the valve itself. Thus, the valve must be capable of undergoing severe shock loads due to the high torque necessary to change the valve position and the rapid shifts in fluid dynamics associated with the control of semi-liquid streams. In addition, the combination of high heat, pressure and shock causes various problems in maintaining an adequate liquid seal over an extended period of operation.
Finally, because the composition and flow characteristics of semi-solids vary considerably, it is essential that valves used to control such fluids be capable of adjustment and/or cleaning periodically during operation without removing the valve from service, ie, without necessitating that the valve or its associated piping be completely disassembled prior to cleaning, adjustment or inspection.
The cylindrical three-way type valve structure in accordance with the subject invention substantially eliminates the above problems. In the preferred embodiment of the invention, a unique knife-edge type cutting plate attached to the periphery of each valve port enhances the sealing capabilities of the valve and effectively eliminates the possibility that the valve or its associated piping will become clogged by large-diameter solids materials. Although the use of a circular lip or plate at or near the entrance of a valve port is known in the art (as shown in U.S. Pat. Nos. 109,906 and 1,084,248), such devices are ineffective in high pressure and temperature applications and have not been used as a means to actually reduce or control the size of solid materials in the fluid stream by actuation of the valve itself.
The present invention, unlike prior art three-way type valves, serves a dual function in that it not only effectively controls the flow of liquids while maintaining a tight seal, it also acts as an additional processing device by virtue of the cutting action of the valve ports themselves. As those skilled in the art can readily appreciate, the metallurgical characteristics as well as the dimensions and configurations of the knife edge may vary considerably depending upon the particular application in which the valve is actually used.
Thus, it is the object of the present invention to provide a tri-port type cylinder control valve having means to reduce the size of solid materials which otherwise might cause a flow restriction in the valve or its associated piping elements. It is a further object of the invention to provide a mounting structure having sealing means which will withstand severe pressure, temperature and shock conditions over an extended period of operation. Still another object of the invention is to provide a valve construction capable of modification while in operation in order to compensate for variations in wear and sealing ability without requiring any disassembly of the valve components.
Other and further objects, features and advantages of the subject invention will appear more fully from the following description of illustrative embodiments taken in conjunction with the appended drawings.